<!DOCTYPE html>
<html>
<head>
  <title>Workday Counter</title>
  <style>
    body {
      width: 200px;
      padding: 10px;
    }
    input, button {
      display: block;
      margin-bottom: 10px;
      width: 100%;
    }
  </style>
</head>
<body>
  <h3>Select Date</h3>
  <input type="date" id="datePicker">
  <button id="calculateButton">Calculate Workdays</button>
  <p id="result"></p>
  <script src="popup.js"></script>
</body>
</html>